final design report non-time-critical removal …various waste oi recyclinl ang d fue oil...

FINAL DESIGN REPORT

NON-TIME-CRITICAL REMOVAL ACTION

BEEDE WASTE OIL SITE PLAISTOW, NEW HAMPSHIRE

RESPONSE ACTION CONTRACT (RAG), REGION

For U.S. Environmental Protection Agency

By Tetra Tech NUS, Inc.

EPA Contract No. 68-W6-Q045 EPA Work Assignment No. 039-NARV-011T

TtNUS Project No. N0306

July 2000

RI00468F

Superfund Records Center SITE: BREAK: OTHER:

Diane M. Baxter George D. Gardner, P.E. Project Manager Program Manager

TETRA TECH MJS, INC. 55 Jonspm Road • Wilmington MA 01887-1020 (978) 658-7899 • FAX (978) 658-7870 • www tetratech com

RACI-EPA-2433

Contract No 68-W6-0045

July 21, 2000

Mr James DiLorenzo U S Environmental Protection Agency One Congress Street, Suite 1100 (HBO) Boston, Massachusetts 02114-2023

Subject Transmittal of Final Design Report Beede Waste Oil, Non-Time-Critical Removal Action RAC I W A No 039-NARV-011T

Dear Mr DiLorenzo

Enclosed is one copy of the Final Design Report for the Non-Time-Critical Removal Action for the Beede Waste Oil Site in Plaistow, New Hampshire The final report addresses all the comments in your letter of April 4, 2000 regarding the Draft Design Report

The PDF electronic version of the final report is being prepared and will be sent to you by email next week

Please contact me at (978) 658-7899 if you have any questions about this transmittal

Very truly yours,

Diane M Baxter Project Manager

PMO- XtAT

DKM rac

Enclosure

H Horahan (EPA) w/o enc R Pease (NHDES) w/enc A Ostrofsky (TIN US) w/enc B Fennelly (TtNUS) w/enc File N0306-1 0 w/o enc / N0306- 3 4 w/enc

TABLE OF CONTENTS FINAL DESIGN REPORT

NON-TIME-CRITICAL REMOVAL ACTION BEEDE WASTE OIL SITE

PLAISTOW, NEW HAMPSHIRE

SECTION PAGE

1.0 INTRODUCTION 1-1 1.1 Project Objectives and Removal Action Plan 1-1 1.2 Report Format 1-2

2.0 PROJECT BACKGROUND 2-1 2.1 Site Location and Description 2-1 2.2 Site History 2-2 2.3 Previous Response Actions 2-4 2.4 Site Characterization 2-6

2.4.1 Previous Studies 2-7 2.4.2 Site Geology and Hydrogeology 2-9 2.4.3 Nature and Extent of LNAPL 2-12 2.4.4 Groundwater Contamination in LNAPL Plume Areas 2-15

2.5 Human Health Risk Evaluation Summary 2-17 2.6 Problem Definition 2-17

3.0 BASIS OF DESIGN 3-1 3.1 General Process Descriptions 3-1 3.2 Design Basis Introduction 3-2 3.3 VEE System Design Basis 3-2

3.3.1 Process Design Criteria 3-3 3.3.2 Process Treatment Scheme 3-5 3.3.3 Performance Requirements 3-7 3.3.4 Residuals Management and Disposal 3-8

3.4 Passive Interceptor Trench Design Basis 3-8 3.4.1 Process Design Criteria 3-9 3.4.2 Performance Requirements 3-11 3.4.3 Residuals Management and Disposal 3-11

4.0 NTCRA PROCESS DESIGN DESCRIPTION AND ANALYSIS 4-1 4.1 VEE System 4-1

4.1.1 Subsystems Description 4-1 4.1.2 VEE System Operation 4-6

4.2 LNAPL Interceptor Trench 4-6 4.2.1 Subsystems Description 4-7 4.2.2 Interceptor Trench Operation 4-8

4.3 ARARs Compliance Analysis 4-8 4.4 Expected System Performance 4-8

RI00468F I Beede Waste Oil, NH

TABLE OF CONTENTS (Cont'd) FINAL DESIGN REPORT



SECTION PAGE

5.0 LAND ACQUISITION/EASEMENT EVALUATION 5-1

6.0 CONSTRUCTION SCHEDULE 6-1

7.0 CONSTRUCTION COST ESTIMATE 7-1

8.0 PROJECT DELIVERY STRATEGY 8-1 8.1 Project Considerations 8-1

8.1.1 Site Considerations 8-1 8.1.2 Material and Equipment Considerations 8-2 8.1.3 Construction Market Considerations 8-3 8.1.4 Project Schedule Considerations 8-5 8.1.5 Project Constraints 8-5

8.2 Contracting Strategy 8-7 8.2.1 Type of Specifications 8-8 8.2.2 Type of Contract 8-8 8.2.3 Subcontract Delivery Procedures 8-9

REFERENCES

TABLES

NUMBER

2-1 Summary of LNAPL PHC, Density, and Viscosity Data

2-10 Summary of Groundwater Total Metals Analysis 2-11 Summary of Groundwater Filtered Metals Analysis 2-12 Summary of Aqueous Water Quality Parameters

2-2 Summary of LNAPL Analysis Results 2-3 Summary of LNAPL Organic Data 2-4 Groundwater and Product Elevation Measurements 2-5 Summary of Historical Groundwater Depths and Product Thickness 2-6 Estimated Product Thickness 2-7 Summary of Groundwater VOCs Analysis 2-8 Summary of Groundwater SVOCs Analysis 2-9 Summary of Groundwater Pesticides/PCBs Analysis

RI00468F ii Beede Waste Oil, NH

TABLE OF CONTENTS (Cont'd) FINAL DESIGN REPORT



TABLES (Cont'd)

NUMBER

4-1 Chemical-Specific ARARs and TBCs 4-2 Location-Specific ARARs and TBCs 4-3 Action-Specific ARARs and TBCs 7-1 Construction Cost Estimate

FIGURES

NUMBER

2-12-24-14-24-34-44-56-1

Site Location Map Site Plan Extraction Wells Extraction Well Zones Piping Layout System Schematic/Details Trench Details Construction Schedule

APPENDICES

AB Design Backup Wetlands Permit

RI00468F III Beede Waste Oil, NH

1.0 INTRODUCTION

This report presents the design of the Non-Time-Critical Removal Action (NTCRA) to address

subsurface plumes of light non-aqueous phase liquid (LNAPL) - or separate phase oil - at the

Beede Waste Oil Superfund site in Plaistow, New Hampshire (the site) Tetra Tech NUS, Inc

[(TtNUS) formerly Brown and Root Environmental] has prepared this document at the request of

the U S Environmental Protection Agency (EPA) under Contract No 68-W6-0045, Work

Assignment 039-NARV-011T

The goal of this document is to provide a complete engineering definition of the LNAPL

extraction and containment systems and the associated treatment and storage subsystems that

comprise the NTCRA

1.1 Project Objectives and Removal Action Plan

The primary objectives of the NTCRA are 1) to remove all recoverable mobile LNAPL from the

subsurface, while minimizing the collection of groundwater, and 2) to prevent any further

migration of LNAPL into the wetlands on the north side of the site

The first objective will be accomplished using vacuum enhanced extraction (also called multi

phase extraction) technology, which employs a central high vacuum blower/pump to extract a

mixture of LNAPL, soil vapor, and water from the subsurface through a network of extraction

wells and transmission pipelines The system will be operated to maximize extraction of LNAPL

and minimize extraction of groundwater Collected vapor, LNAPL, and water will be processed

through two separators (air/fluid and oil/water), the air will be treated by granular activated

carbon (GAC), the fluids will be transferred to separate storage tanks and disposed off site

approximately once per month

The second objective will be accomplished through extension of the existing LNAPL interceptor

trench by 24 feet to capture the western edge of the plume The existing trench is constructed of

concrete galley chambers placed end to end to form an open channel The upgradient side of

the trench is perforated to allow entry of water and LNAPL, the downgradient side of the trench

has an impermeable barrier to prevent outflow of LNAPL Passive skimming units are installed

within the trench to collect LNAPL that migrates into and is contained within the trench The

RI00468F 1-1 Beede Waste Oil NH

1.2

trench extension will be installed and equipped with a passive skimmer unit at the beginning of

NTCRA construction, so that containment is assured as early as possible

Report Format

This document includes 8 sections Section 1 0 is this brief introduction Section 2 0 provides

project background Section 3 0 presents the basis of the NTCRA design Section 4 0 provides

a detailed description and evaluation of the NTCRA components Section 5 0 presents an

evaluation of the need for land acquisition or easements Section 6 0 is the construction

schedule Section 7 0 includes the detailed construction cost estimate and value engineering

assessment Section 8 0 presents the project delivery and contracting strategy


2.0 PROJECT BACKGROUND

This section presents the site location and description, summarizes the operations history and

previous removal actions that have been conducted at the site, and defines the problem that is

to be addressed by the NTCRA

2.1 Site Location and Description

The Beede Waste Oil site is located at 7 Kelley Road in Plaistow, New Hampshire The site is

comprised of two parcels occupying approximately 39 acres in a generally residential area

Parcel 1 (approximately 22 acres owned by New Hampshire Realty Trust) was the site of

various waste oil recycling and fuel oil distribution operations from the 1920s through 1994

Parcel 2 (approximately 17 acres owned by Sun Realty Trust) was used mainly for commercial

sand and gravel operations Operations on Parcel 1 over the years resulted in the release of

various substances including petroleum products, polychlormated biphenyls (PCBs), and

chlorinated solvents to soil and groundwater beneath the site, and resulted in the presence of

three large LNAPL plumes floating on the groundwater table beneath Parcel 1 These plumes

are the focus of the NTCRA No contaminant source areas have been identified on Parcel 2 A

site locus map is provided as Figure 2-1 A site plan showing significant site features is

presented as Figure 2-2

Parcel 1 has road frontage on Kelley Road and is also bordered by Kelley Brook and

associated wetlands, residential properties, Parcel 2, and undeveloped woodland Access to

Parcel 1 is currently restncted by a chain link fence that surrounds the parcel except for a

portion of its border with Parcel 2 Parcel 2 has frontage on Old County Road and is also

bordered by residential properties, Kelley Brook, and Parcel 1 Access to Parcel 2 is partially

restncted by a chain link fence along its southeastern border and by Kelley Brook, which runs

along its northern border Both parcels are zoned as medium density residential property

Two buildings are currently situated on the site an approximately 10,000-square foot

commercial building with a 4,000-square foot canopied drum storage area is located near the

site entrance on Parcel 1 This building, constructed around 1980, was used as the Beede

Waste Oil/Cash Energy office and for laboratory analysis, burner repair, used oil sludge

RI00468F 2-1 Beede Waste Oil, NH

2.2

processing, and vehicle maintenance (Aries, 1991 - Preliminary Hydro-geologic Study) The

second existing building is a rented residence located at the northeast end of Parcel 2 along

Old County Road A third building was formerly located on Parcel 1 This approximately

6,000-square foot building was used for antifreeze recycling, vehicle maintenance, and office

and storage space, was located approximately 300 feet east of the site entrance This older

building was in poor condition and was demolished in April 1998 to allow safe access for

investigation of the underlying materials A portion of the building slab remains

The topography on Parcel 1 is generally flat, with the exception of the northeastern section,

which slopes toward Kelley Brook, and three large man-made depressions an unlined

containment area in the center of the parcel, which previously contained several large above

ground storage tanks (ASTs), Surface Water Retention Pit (SWRP) No 1 near the site

entrance, and SWRP No 2 on the northeastern side of Parcel 1 In addition, several piles of

contaminated soil and debris are present on the site, mainly on Parcel 1 The soil piles are

covered with tarpaulins The site is largely unpaved, except in the vicinity of the Kelley Road

entrance and surrounding the Beede Waste Oil/Cash Energy building

Site History

The site is an inactive waste oil recycling and virgin fuel oil storage and distribution facility Oil-

related activities at the site began around 1926, when Robert Beede operated a waste oil

recycling facility at the site, receiving and storing waste oils on site and then reselling usable

oils to asphalt manufacturing facilities and to towns for dust suppression on roadways From

1962 to 1992, Beede Waste Oil, Cash Energy, Inc, and a senes of related subsidiaries and

affiliates operated at the site Operations conducted at the site included fuel oil storage and

distribution, used oil recycling and distribution, gasoline/water separation, used anti-freeze

recycling/reclamation, and cold-patch asphalt batching using petroleum-contaminated soils

Beede Waste Oil was first permitted as a Resource Conservation and Recovery Act (RCRA)

hazardous waste transporter and waste oil blender/burner in 1980 Beede Waste Oil and Cash

Energy discontinued site operations in the fall of 1992 From the fall of 1992 until August

1994, Tn-State Resources operated a virgin fuel oil storage and distnbution business No

commercial operations have occurred at the site since August 1994 (NHDES, 1995)


Beede Waste Oil had a history of permit violations and citations for non-compliance with

environmental laws. From 1991 to 1993 the state government tried to compel the company to

correct permit violations and begin cleanup and monitoring efforts. These efforts culminated in

the Rockingham County Superior Court issuing a preliminary injunction in December 1992 that

required site owners to begin removal of free product oil from the groundwater and surface

water; test off-site drinking water wells and provide alternate water supplies, if necessary;

cover and maintain soil piles; conduct a site investigation; and develop and implement a

remedial action plan. In January 1993, in the absence of acceptable action by the site owners,

the New Hampshire Department of Environmental Services (NHDES) began conducting many

of the tasks required by the December 1992 injunction.

The site was placed on the Comprehensive Environmental Response, Compensation, and

Liability Information System (CERCLIS) list in December 1993 and on the National Priorities

List (NPL) for uncontrolled hazardous waste sites in December 1996.

Between November 1996 and January 1998 EPA and NHDES jointly conducted a time-critical

removal action to remove and dispose of the waste oil, sludge, and water from the nearly 100

ASTs and 800 drums that remained on the site. The actions also included cleaning,

dismantling, and removing the ASTs and removing the drums from the site. These removal

actions are discussed in more detail in Section 2.3.

Between February 1995 and July 1998 NHDES's contractor (Sanborn, Head and Associates

[SHA]) conducted field investigations to support the Remedial Investigation (Rl) for the site.

The comprehensive Rl report for the site, which will present the site investigation results and

the human health and ecological risk assessments, is being prepared.

In the fall of 1997 B&RE (now TtNUS), under contract to EPA, conducted a treatability study

and field investigation at the site to evaluate LNAPL recovery and containment technologies

and better delineate the extent and volume of LNAPL present in the subsurface. The

treatability study included installing an LNAPL interceptor trench at the edge of the wetlands to

test containment technologies. The trench was left in place after the study to prevent further

migration of LNAPL into the wetlands. The trench was initially maintained by EPA and NHDES.

It has been maintained by TtNUS since July 1998.


2.3

In June 1998 B&RE completed an Engineering Evaluation/Cost Analysis (EE/CA) for the site.

The EE/CA report presented the development and evaluation of an LNAPL remediation

approach for the site. The EE/CA was the basis for selection of the preferred NTCRA remedy

and is the basis of the design presented in this report.

In September 1998 EPA's Action Memorandum, which summarizes the selected NTCRA for

the site, was approved. The selected NTCRA consists of installing a Vacuum Enhanced

Extraction (VEE) system in the three LNAPL plume areas to remove mobile LNAPL and

extending the existing LNAPL interceptor trench 24 feet to the west to ensure complete

containment of the LNAPL plumes and prevent further migration of LNAPL into the Kelley

Brook wetlands.

Previous Response Actions

This section summarizes response activities that have been conducted at the site and activities

conducted at surrounding properties to limit exposure to site contaminants. This summary was

compiled from the Site and Waste Characterization Report (SHA, 1995), Petroleum Release

Assessment (Aries Engineering, Inc., 1991), the Hazard Ranking Package (EPA, 1996), and

discussions with representatives from EPA and NHDES. More detailed descriptions of the

activities are provided in the referenced reports.

• 1983 - The owner of the Elwell residence (east of the site) installed a bedrock well as

an alternate water supply after analysis of water from the existing overburden supply

well in October 1983 indicated the presence of contaminants including trichloroethene

(TCE) above the Safe Drinking Water Act (SDWA) maximum contaminant level (MCL).

• November 1989 - Site operators reportedly removed eight USTs containing gasoline,

used oil, No. 2 fuel oil, and other unspecified substances. The removals were not

documented.


• 1990 - Site operators installed an on-site bedrock well (WS-2) as an alternate water

supply for the Carrington residence (immediately north of the site) after benzene was

detected in June 1990 above the MCL in water from the existing overburden supply

well.

• June 1991 - Site operators removed the 140,000-gallon waste oil LIST and two smaller

USTs. Aries Engineering observed and documented the LIST removals. Oil-stained

soils were observed in the tank excavation; approximately 50 cubic yards of

contaminated soils were removed from the tank excavation and stockpiled on site.

• November 1991 to January 1992 - Site operators installed two oil recovery wells to

remove LNAPL from the subsurface.

• February 1992 - NHDES began maintaining oil absorbent booms and pads to collect

LNAPL seeping into the Kelley Brook wetlands. NHDES continued to maintain

absorbent booms in the wetlands until the installation of an interceptor trench by B&RE

in the fall of 1997.

• February to March 1992 - Site operators excavated two interceptor trenches between

the older site building (now demolished) and the edge of the wetlands. During

excavation of the more southerly "upper" trench, several drums of liquid wastes

containing high concentrations of VOCs were encountered and removed from the

trench. According to representatives of EPA and NHDES, neither trench was effective

for containment or collection of LNAPL. An oil sheen was occasionally observed in the

"upper" trench when groundwater levels were high. Product was never observed in the

more northerly "lower" trench, adjacent to the wetlands.

• November 1992 - Site operators discontinued oil recovery efforts at the recovery wells

and trenches. Subsequently, NHDES initiated oil recovery efforts. NHDES removed

approximately 7,900 gallons of hazardous waste oil/water between December 1992

and May 1994.


• 1995 - NHDES installed point-of-entry treatment units at three residential properties

and one commercial property adjacent to the site after VOC contamination above

drinking water standards was detected in water from their bedrock wells. These four

properties are served by two wells: one supplying Howard Manor Condominiums (12

housing units) and the other supplying the Joray and Armstrong residences and an

insurance business.

• 1996 to 1998 - EPA and NHDES conducted a time-critical removal action to remove the

hazardous and non-hazardous waste oil remaining in nearly 100 ASTs and 800 drums

on the site. The drums and drum contents were removed and disposed off site. The

AST contents (oil, sludge, and water) were removed and disposed off site. The ASTs

were then cleaned, dismantled, and removed from the site. The removal action was

completed in January 1998. The oil in the tanks and drums contained varying

concentrations of PCBs and chlorinated compounds that caused some of it to be

regulated under the Toxic Substances Control Act (TSCA) and RCRA. The oil was

characterized as TSCA waste (containing greater than 50 parts per million (ppm)

PCBs), RCRA (D- and F-listed) waste, RCRA and non-RCRA waste containing 2 to 49

ppm PCBs, off-specification recyclable oil with less than 2 ppm PCBs, and on-

specification recyclable oil with less than 2 ppm PCBs.

• Fall 1997 - B&RE installed a pilot-scale LNAPL interceptor trench at the edge of the

wetlands. The trench was installed as part of a treatability study conducted to test

LNAPL collection and containment technologies. After the study was completed, the

trench was left in place to prevent further migration of LNAPL into the wetlands and

passive skimmers tested during the treatability study were deployed in the trench to

collect LNAPL. The trench was initially maintained by EPA and NHDES. It has been

maintained by TtNUS since July 1998. As of July 2000 approximately 140 gallons of

waste oil have been removed from the trench.

Site Characterization

This section summarizes the results of the site characterization efforts conducted by B&RE

and others pertinent to the LNAPL contamination and remediation at the BWO site.


2.4

2.4.1 Previous Studies

Several investigations have been conducted at the site by consultants to NHDES, EPA, and

the site owners. This section provides brief summaries of the primary data sources used in

evaluating and selecting the NTCRA remedy. The full citations for the referenced reports are

provided in the reference section.

Aries Engineering. Inc. (Aries), 1991-1992 - Site operators retained Aries to conduct a

petroleum release assessment and additional site investigations. Aries installed 25 monitoring

wells; excavated test pits; collected and analyzed soil, groundwater, and LNAPL samples;

performed a geophysical survey; and documented the removal of three USTs. Aries produced

three reports that were used for reference in preparing the EE/CA: Petroleum Release

Assessment, September 1991; Preliminary Hydrogeologic Study, November 1991; and Test Pit

Excavations and Ground Penetrating Radar Survey, March 1992. These reports were used

principally for historical and geologic/hydrogeologic data.

SHA. 1995-1996 - NHDES retained SHA to characterize sources of soil, groundwater, and

surface water contamination at the site; evaluate the extent, fate, and transport of site

contaminants; and characterize wastes stored at the site to identify disposal options. Site

characterization activities included performing a soil gas survey, excavating test pits, installing

15 overburden monitoring wells; collecting and analyzing soil, groundwater, surface water,

sediment, and LNAPL samples; and conducting field permeability tests. These activities were

summarized in SHA's September 1995 report: Site and Waste Characterization, Beede Waste

Oil/Cash Energy Site. This and four other SHA reports (dated January, April, September, and

December 1996) documenting additional rounds of groundwater and surface water monitoring,

sampling, and analysis were the principal sources of chemical, hydrogeological, and historical

data used in preparing the EE/CA.

B&RE Treatabilitv Study (1997)

B&RE conducted a treatability study to evaluate LNAPL recovery and containment

technologies. The LNAPL Recovery Treatability Study involved constructing a 100-foot long


interceptor trench immediately upgradient of the LNAPL seep area at the edge of the Kelley Brook

wetlands, constructing extraction and monitoring wells in three plume areas, and testing various

LNAPL collection technologies within the trench and the extraction wells.

The technologies tested in the trench were passive skimmers and skimmer pumps for LNAPL-

only collection, and dual pump systems for active LNAPL collection and groundwater

depression. The technologies tested in the extraction wells included skimmer pumps and total

fluids pumps for LNAPL-only collection, total fluids pumps for LNAPL collection and

groundwater depression, and vacuum enhanced extraction (VEE) for active LNAPL collection

with minimal collection of groundwater.

Based on the results of the treatability study, vacuum enhanced extraction was determined to

be the most viable technology for LNAPL collection, and the interceptor trench with passive

skimmers was determined to be the most viable technology for LNAPL containment. Complete

results of the treatability study are reported in the LNAPL Recovery Treatability Study and

Field Investigation Report (B&RE, April 1998).

B&RE Field Investigations (1996 and 1997)

B&RE performed limited field monitoring and sampling in December 1996 and January 1997,

and conducted a more intensive field investigation from October to December 1997 as part of

the LNAPL Recovery Treatability Study. The investigations were conducted in support of the

EE/CA, to better characterize the nature and extent of LNAPL, and characterize groundwater

beneath the LNAPL to evaluate treatment options.

LNAPL investigation activities conducted in December 1996 and January 1997 included

monitoring product and water levels, sampling product for chemical and physical (viscosity)

analysis, and conducting product drawdown tests to evaluate product recovery.

The LNAPL field investigation conducted in October-December 1997 consisted of advancing

soil borings; collecting soil samples for visual observation and field screening; installing

monitoring wells; recording groundwater and LNAPL elevations in the new and existing

monitoring wells; conducting product recovery tests in a subset of the monitoring wells and


using the test results to estimate the actual thickness of mobile LNAPL in the aquifer,

collecting LNAPL samples from several locations to evaluate the physical and chemical nature

of the product, and collecting groundwater samples for chemical analysis Complete results of

the field investigations are reported in the LNAPL Recovery Treatability Study and Field

Investigation Report (B&RE, April 1998)

SHA Remedial Investigation 1996-1997

SHA conducted extensive investigations during 1996 and 1997 to support the site Remedial

Investigation Activities included investigation of potential waste areas, characterization of soil,

groundwater, surface water, and sediment, and characterization of site geology and

hydrogeology The results of these investigations will be presented in a Remedial

Investigation Report that is expected to be completed in late 2000 SHA has provided TtNUS

and EPA some preliminary data from these investigations Because these data were received

after submittal of the EE/CA and signing of the Action Memorandum, the data were not

considered in selection of the NTCRA remedy, however any data pertinent to the NTCRA were

considered in the design

2.4.2 Site Geology and Hydrogeology

This section presents a general description of the geologic and hydrogeologic features of the

site pertinent to the NTCRA The discussion presented here is based on data and

interpretations presented by SHA in its Site and Waste Characterization Report (1995) and

available remedial investigation data

Overburden Geology

The subsurface stratigraphy at the site consists of five principal soil units These are, in order

from top to bottom, gravelly sand, fine sand, sand, grey sand, and till These units were

observed over most of the site, except for the upper gravelly sand, most of which has been

excavated from Parcel 2 A lower gravelly sand unit is also present below the fine sand in the

eastern and southern portions of Parcel 2 The transitions between soil units are typically


gradational, however, in some borings, a fine to coarse sand or gravelly sand was observed

below or mterstratified with the fine sand unit

Based on field observations and sieve analysis, the gravelly sand unit is characterized as a

medium dense, brown, fine to coarse sand with approximately 5 to 40 percent gravel and up to

20 percent silt Where present, the upper gravelly sand unit ranges from 15 to 40 feet thick

and lies largely above the water table

The fine sand unit is characterized as a medium dense, brown, fine sand with approximately 5

to 50 percent silt In some locations this unit contains layers of gravelly sand and/or sand" This

unit is typically 10 to 45 feet thick This unit is typically overlain by gravelly sand and underlain

by till or gray sand, the transition to adjacent units is typically gradational

The sand unit is characterized as medium dense to dense, light brown, fine to coarse sand

with approximately 10 to 20 percent silt, and possibly containing layers of gravelly sand or fine

sand This unit ranges from less than 5 feet to approximately 25 feet thick

The grey sand is characterized as a medium dense to very dense, gray, fine to medium sand

with approximately 5 to 30 percent silt This unit ranges from less than 5 feet to approximately

15 feet thick

Based on field observations and sieve analysis there are two types of till units at the site, a

sandy till and a clayey till The sandy till is characterized as a very dense, gray, fine to coarse

sand with up to 40 percent silt and approximately 5 to 30 percent gravel In general, the sandy

till ranges from approximately 10 to 75 feet thick In many areas of the site this unit is

underlain by clayey till The clayey till is characterized as a hard gray, clayey silt to silty clay

with approximately 20 to 60 percent sand and less than 15 percent gravel This unit ranged

from approximately 10 to 35 feet thick

In addition to the three principal soil types, several secondary units were identified at the site,

including topsoil, solid waste fill, soil fill, clay, peat, and a deep fine sand unit The secondary

units most pertinent to LNAPL removal activities are descnbed below


• Solid waste fill was observed in approximately 30 test pits on the northeast side of

Parcel 1, in the area of the former older site building and northeast toward Kelley

Brook. The thickness of the solid waste fill ranged from approximately 2 to 15 feet. It

was occasionally underlain by up to 10 feet and overlain by up to 3 feet of soil fill. The

solid waste fill was estimated to cover an area of approximately 30,000 square feet (sf),

with a volume of approximately 7,800 cubic yards (cy). The solid waste fill is

characterized as brown to black (stained) fine to coarse sand with various amounts of

wire, brick, metal (including car parts), wood, plastic, rubber (including tires), glass,

cloth, and other miscellaneous items. This area of the site appears to have been a

wetland prior to filling.

• Soil fill was encountered to depths of 4 to 8 feet in test pits TP-5 and TP-6, and in

boring SH-5, in the apparent location of the former lagoon, which was filled during the

mid-1970s. The fill material consisted of fine to coarse sand with varying amounts of

gravel and silt, and in some locations, wood and metal debris.

• Approximately 0.3 feet of clay was observed at a depth of 8 feet below ground surface

in boring SH-5, which is located at the estimated center of the former lagoon. The clay

layer appears to be the bottom of the former lagoon.

• Peat deposits approximately 1 to 2 feet thick were observed beneath the fill material in

boring SH-6 and test pit TP-2, near the west interceptor trench. It is presumed that the

peat represents the original ground surface at these locations.

Hvdrogeology

Groundwater flow directions were estimated by SHA based on groundwater levels measured

during four monitoring rounds from September 1997 and September 1998. In general,

groundwater flow in the shallow overburden beneath Parcel 1 is to the northeast and exhibits a

slight convergence toward the center of the parcel. On Parcel 2, the shallow groundwater flow

direction is controlled primarily by the location and surface water levels of Kelley Brook. The

presence of a beaver dam in Kelley Brook on the northeast side of Parcel 2 has resulted in

elevated surface water levels in the brook upstream of the dam. This results in generally


northeast to east shallow groundwater flow in the central and western portion of Parcel 2.

Close to the brook, upstream of the beaver dam the shallow groundwater flows southeasterly

to southerly away from the brook. Downstream of the beaver dam, in the east and southeast

portion of Parcel 2, the shallow groundwater flows radially toward Kelly Brook

The Intermediate and deep groundwater flows generally toward the east-northeast, similar to

shallow groundwater. Based on limited bedrock groundwater elevation data, groundwater flow

in the bedrock aquifer appears to be generally toward the east to southeast.

Hydraulic conductivities were estimated by SHA for the principal overburden soil units using

several estimation methods including correlation to grain size and analysis of slug and

borehole permeability tests (SHA, 1995). The estimated average hydraulic conductivities for

the five principal overburden units (gravelly sand, fine sand, sand, grey sand, and till) were:

gravelly sand 5 to 20 ft/day; fine sand 1 to 10 ft/day; sand 5 to 20 ft/day; grey sand 5 to 20

ft/day; and till 0.001 to 5 ft/day (SHA, 1999).

2.4.3 Nature and Extent of LNAPL

The LNAPL at different locations at the site varies in both chemical and physical composition.

In general, the LNAPL consists of various mixtures of petroleum products including fuel oil

No. 2/diesel, gasoline, kerosene, and lubricating oil. The LNAPL also contains a relatively

smaller fraction of chlorinated and aromatic volatile organic compounds (VOCs),

polychlorinated biphenyls (PCBs), metals, and low concentrations of a few pesticides. All

LNAPL samples collected were determined to be lighter than water. The viscosities of the

LNAPL samples collected ranged from 4.09 to 130.4 centiStokes.

The laboratory analysis results for the product samples are summarized in Tables 2-1, 2-2

and 2-3. Groundwater elevation and LNAPL thickness data are summarized in Tables 2-4, 2-5, and

2-6. The LNAPL characterization and the delineation of the lateral extent, thickness, and

volume of each of the LNAPL plumes is summarized below. The plume delineations are

presented on the site plan (Figure 2-2).

RI00468F 2-12 Beede Waste Oil, N H

Plume 1: Former Lagoon Plume - The LNAPL plume in the former lagoon area is estimated to

be approximately 250 feet long and 180 feet wide, encompassing an area of approximately

0.87 acres. The maximum estimated thickness of mobile LNAPL in the former lagoon plume is

0.56 feet at well BR-10. The estimated volume of mobile LNAPL in the plume is 14,300

gallons.

The LNAPL collected from monitoring wells SH-5, SH-7, and AE-11s in the former lagoon area

is characterized as largely lubricating oil, with lesser to minor amounts of gasoline and light fuel

oil. VOCs in the LNAPL consist of aromatic VOCs, chlorinated VOCs, and volatile petroleum

hydrocarbons (PHCs). PCBs were also detected in the three product samples at

concentrations ranging from 11 mg/kg to 37 mg/kg. The density of the product samples

ranged from 0.86 to 0.88 g/mL. The viscosity, measured in samples from SH-5 and AE-11S,

ranged from 121.4 to 130.4 centiStokes. Product samples from this plume were not analyzed

for metals, pesticides, or SVOCs.

Plume 2: SWRP No. 1 Plume - The LNAPL plume in the SWRP No. 1 area is estimated to be

approximately 160 feet long and up to 110 feet wide, encompassing an area of approximately

0.30 acres. The maximum estimated thickness of mobile LNAPL in the plume is 0.11 feet at

well BR-18. The estimated volume of mobile LNAPL in the plume is 2,000 gallons.

The product collected from the SWRP No. 1 plume in monitoring well AE-4 is described as

kerosene; in AE-3, product is described as kerosene and weathered fuel oil No. 2/diesel. The

LNAPL samples analyzed for VOCs indicated a moderate concentration of aromatic VOCs, no

chlorinated VOCs, and a high concentration of volatile PHCs. Total PCBs concentrations of 21

mg/kg and 46 mg/kg were detected in LNAPL samples from AE-3 and AE-4. Metals detected

in AE-3 included arsenic, chromium, lead, and selenium. SVOCs detected in AE-3 included

several PAHs and bis(2-ethylhexyl) phthalate. The density of LNAPL in monitoring well AE-3

was 0.83 g/mL. Product from AE-4 was not analyzed for density due to insufficient volume.

Product collected from BR-18 contained primarily diesel range TPH and had a viscosity of 4.09

centiStokes. The product was observed to be a clear, light brown fluid.

Evaluation of product analytical results indicates that this plume may merge with the LIST/AST

plume in the vicinity of BR-27. The viscosity (23.8 centiStokes) and TPH analysis of the


product at this well appear to be approximately the average of the viscosity and TPH

determined for well BR-18 in the SWRP No. 1 plume and BR-E02 in the UST/AST plume.

Plume 3: UST/AST Plume - This large plume appears to originate from the former 140,000

gallon UST and nearby former ASTs. However, the composition of LNAPL in different areas of

the plume varies, possibly because different types of product were stored in (and released

from) the UST and ASTs at different times during the facility's operation. Additionally, the

characteristics of the product may have changed over time, as the product migrated, due to

chemical or biological processes.

The plume is estimated to be approximately 320 feet long and up to 210 feet wide,

encompassing an area of approximately 1.42 acres. The downgradient extent of the plume is

delineated by an observed LNAPL seep location in the wetlands adjacent to Kelley Brook

(SW-2). The maximum estimated thickness of mobile LNAPL in the plume is 0.65 feet at well

BR-22. The estimated volume of mobile LNAPL in the plume is 26,700 gallons.

Two locations were identified within the UST/AST plume area where little or no mobile product

was present, despite the presence of a significant amount of product in nearby wells. The lack

of product may be explained by the presence of landfill materials or other low conductivity

materials in or upgradient of these locations that are obstructing and diverting product flow

around these areas.

The LNAPL collected from wells AE-8, AE-9, and AE-16 in the northwest portion of the plume

is characterized as primarily lubricating oil with some fuel oil No. 2/diesel and possible minor

amounts of weathered gasoline. The TPH analysis of product from BR-E02 is consistent with

this characterization (principally motor oil-range TPH, with some diesel-range, and little

gasoline-range TPH). The density analysis of the LNAPL ranges between 0.88 and 0.94 g/mL

and the viscosity of the LNAPL samples were 49 centiStokes (AE-9) and 54.3 centiStokes

(BR-E02). Samples collected from wells AE-8 and AE-9 contained aromatic VOCs, chlorinated

VOCs, volatile PHCs, and PCBs. Total PCBs concentrations ranged from 32 mg/kg to 67

mg/kg. Metals detected in product samples from AE-9 and AE-16 were arsenic, beryllium

(AE-16 only), chromium, lead, and zinc (AE-9 only). SVOCs detected in AE-9 included several

PAHs and bis(2-ethylhexyl) phthalate. Pesticides alpha BHC, beta BHC, and dieldrin, were


detected at low concentrations (less than 02 mg/kg) in AE-16 The product pumped from

wells in the area of AE-8 and AE-9 during the treatability study was observed to be an

emulsified mixture that separated into two distinct product layers and, in some cases, a third

layer of a light green liquid (similar to ethylene glycol)

The LNAPL collected from monitoring wells SH-6 and SH-10 downgradient of SWRP No 2 is

characterized as lubricating oil, kerosene, and possibly lesser fuel oil No 2/diesel and minor

weathered gasoline The sample from SH-6 contained more lubricating oil than kerosene, the

sample from SH-10 contained somewhat more kerosene than lubricating oil The TPH analysis

of product from BR-22 is consistent with this characterization (principally motor oil-range TPH,

with some diesel-range, and little gasoline-range TPH) The density of the LNAPL was

determined to be 0 87 g/mL in SH-6 and 0 85 g/mL in SH-10 The viscosity of the LNAPL

sample was 19 4 centiStokes in SH-10 and 43 3 centiStokes in BR-22 The LNAPL samples

analyzed for VOCs indicated a high concentration of aromatic VOCs, moderate concentrations

of chlorinated VOCs, and a high concentration of volatile PHCs Total PCB concentrations

exceeding the TSCA waste criterion of 50 mg/kg were detected in LNAPL samples from both

monitoring wells Product samples from this plume were not analyzed for metals, pesticides,

or SVOCs The product in wells SH-6 and SH-10 was similar in appearance clear, golden

product similar to clean motor oil

The product collected in the LNAPL interceptor trench, at the downgradient limit of the plume

had a higher viscosity (107 centiStokes), a somewhat different chemical characteristics (higher

concentration of lubricating oil/motor oil, with very little diesel or gasoline range TPH), and a

different appearance than product observed in other areas of the plume The product is a dark

brown/black, dirty oil, similar in composition, viscosity, and appearance, to that observed in the

former lagoon plume, indicating that the this portion of the plume (the leading edge) may have

been released from the LIST during the same time period that the former lagoon was in use

(1962-1970)

2.4.4 Groundwater Contamination in LNAPL Plume Areas

A groundwater sampling and analysis program was conducted during the treatability study to

determine the chemical constituents in groundwater extracted dunng collection of LNAPL The


objective of the program was to characterize the extracted groundwater to evaluate treatment and

disposal/discharge options for groundwater that will be collected by the LNAPL extraction system

during the NTCRA. This section presents the results of this groundwater characterization.

Two types of samples were collected. Groundwater samples were collected from the effluent side

of the oil/water separator at various times during operation of the treatability study, while a single

groundwater extraction system was operating. These samples were collected to determine the

characteristics of the groundwater at each extraction point. Grab-samples were collected from each

groundwater storage tank (frac tank) when it was full. These samples were collected to represent

the mixed waste stream that may be generated and would require treatment or disposal during full-

scale operation. For detailed discussion of sampling methods, refer to TS/FI Report and the

Sampling and Analysis Plan (B&RE October, 1997).

The groundwater samples were analyzed for VOCs, SVOCs, pesticides/PCBs, total metals,

dissolved metals, ethylene glycol, BOD5, COD, TOC, oil and grease, TSSs ammonia, and total

phosphorous. The analytical results were compared against New Hampshire ambient

groundwater quality standards (AGQS) and federal ambient water quality criteria (AWQC) to

identify compounds in the groundwater likely to exceed potential discharge criteria. This

evaluation is summarized below. The analytical results are presented in Tables 2-7 through 2-12.

Several VOCs (methylene chloride; 1,2-dichloroethene; 1,1,1-trichloroethane; benzene;

trichloroethene; tetrachloroethene; and toluene) were detected at concentrations exceeding

AGQS in the samples collected from the effluent of the oil/water separator. Only two VOCS

(1,2-dichloroethene and 2-butanone) were detected at concentrations exceeding AGQS in the

frac tank samples. There were no VOC exceedences of AWQC.

Low concentrations of several SVOCs, primarily PAHs, were detected in all groundwater

samples. A few compounds (naphthalene, benzo(a)anthracene, and chrysene) exceeded

AGQS and two compounds (phenanthrene and butylbenzylphthalate) exceeded AWQC

values. Exceedences were noted in both effluent and frac tank samples.

Two pesticides (aldrin and dieldrin) were detected at concentrations exceeding AGQS in both

effluent and frac tank samples. Several pesticides were detected at concentrations exceeding


AWQC in both effluent and frac tank samples One PCS (aroclor 1260) was detected

exceeding both AGQS and AWQC in both effluent and frac tank samples

Several metals were detected in groundwater samples at concentrations exceeding AGQS and

AWQC values Generally the filtered samples had significantly lower metals concentrations

than the unfiltered samples, but typically the same exceedences were noted in both Only

aluminum and arsenic exceeded AGQS in the unfiltered samples, but not the filtered samples

Compounds detected at concentrations greater than AGQS were iron, lead, and manganese

Iron, lead, mercury, silver, and zinc were detected at concentrations greater than AWQC

2.5 Human Health Risk Evaluation Summary

The streamlined human health risk assessment conducted for the EE/CA concluded that there

is a clear human health risk associated with LNAPL-related contaminants present in

groundwater downgradient of the site Contaminants associated with LNAPL have been

detected at concentrations exceeding drinking water standards in groundwater from private

residential wells located downgradient of the LNAPL plumes

There is also a potential human health nsk associated with exposure to LNAPL and LNAPL-

related contaminants at the site and in the adjacent wetlands and Kelley Brook Adults and

children fishing in Kelley Brook or walking in the wetland could come into contact with the

LNAPL or contaminated surface water or sediment Installation of the LNAPL interceptor

trench has partially contained LNAPL migration, but LNAPL continues to migrate toward the

wetlands, and remains a primary source of ongoing groundwater contamination

2.6 Problem Definition

Three subsurface LNAPL plumes are present at the site, covering a total area of approximately

2 6 acres The LNAPL is a continuing source of contamination to the aquifer beneath the site,

which is the pnmary drinking water supply for the surrounding residential area LNAPL-related

contaminants have been detected in several private water supply wells downgradient of the

site The LNAPL is also migrating toward Kelley Brook and the adjacent wetlands, where

people may come into contact with the LNAPL or impacted surface water or sediment


The streamlined human health risk assessment concluded that there is a potential threat to

humans from household use and consumption of groundwater impacted by LNAPL-related

contaminants; direct contact with contaminants in the LNAPL seep areas; and ingestion of

impacted sediment. Site conditions also pose a potential threat to the environment and

ecological receptors from seepage of LNAPL into the Kelley Brook wetlands.

Based on these factors it was determined that an NTCRA is appropriate to mitigate the risks to

human health and the environment posed by LNAPL partitioning into the groundwater and

seeping into wetlands at the site.


3.0 BASIS OF DESIGN

The purpose of this section is to provide brief descriptions of the NTCRA system components

and to define the design basis for the LNAPL extraction and containment systems that comprise

the NTCRA.

3.1 General Process Descriptions

The selected NTCRA remedy consists of installing a Vacuum Enhanced Extraction (VEE) system

in the three LNAPL plume areas to extract the mobile LNAPL, and extending the existing LNAPL

interceptor trench 24 feet to the west to contain the LNAPL and prevent it from migrating into the

Kelley Brook wetlands. Brief descriptions of the LNAPL extraction and containment systems are

provided in this section.

LNAPL Extraction System (VEE System)

The VEE system employs a liquid ring vacuum pump to recover LNAPL from the subsurface in

a high velocity stream with a mixture of groundwater and soil vapor. A network of extraction

wells, equipped with extraction tubes (commonly called drop tubes) provides access to the

LNAPL layer. The drop tubes are ultimately connected to the vacuum pump and associated

equipment via a system of above ground transmission pipelines.

Once the LNAPL, groundwater, vapor mixture is drawn from the well, it is conveyed to the

extraction equipment through the network of transmission lines. The mixture is then separated,

the air is passed through a vapor phase granular activated carbon (GAC) vessel to remove

volatile organic compounds (VOCs), and the water and LNAPL are transmitted into separate

storage tanks to await off-site disposal.

LNAPL Containment System (Interceptor Trench)

The LNAPL interceptor trench is an open-channel type recovery trench, constructed of pre-cast,

perforated, concrete galley structures laid end to end in an excavated trench to form a

continuous channel. The interceptor trench is located in a topographically and hydraulically low

area at the site. LNAPL, located on the surface of the aquifer, moves downgradient with the


groundwater and is eventually intercepted by the trench. As the LNAPL and groundwater

infiltrate the trench, floating devices passively skim the LNAPL from the surface of the

groundwater. These floating devices are called passive skimmers. Oil collected in the skimmers

is stored on site until disposal at an off-site facility. The interceptor trench installed for the

treatability study is being extended 24 feet to the west as part of the NTCRA.

3.2 Design Basis Introduction

The design basis for the NTCRA is primarily derived from the results of the 1997 treatability

study conducted by B&RE, although the results of previous investigations were also considered.

The purpose of the treatability study was to evaluate the effectiveness of several technologies

for recovery and containment of LNAPL.

To determine the effectiveness for LNAPL removal from the groundwater surface, three

remedial alternatives were tested during the treatability study. These technologies included

skimmer pumps, vacuum enhanced extraction (VEE), and dual pump extraction. Of the three

technologies, VEE proved to be the most effective for removing LNAPL while minimizing the

collection of groundwater (B&RE, 1998a).

To determine the effectiveness of interceptor trench technology to act as a barrier to LNAPL

migration, the treatability study also included the installation of an interceptor trench and the

testing of three LNAPL collection technologies within the trench. These technologies included

passive skimmers, skimmer pumps, and a dual pump system. Of the three technologies, the

passive skimmers were the most effective for LNAPL removal while minimizing the collection of

groundwater (B&RE, 1998a).

The NTCRA design is in accordance with the EPA Action Memorandum approved for the site in

September 1998. The basis for design and the major components of the NTCRA are presented

in Sections 3.2 and 3.3.

3.3 VEE System Design Basis

The results of the treatability study provided the initial design basis for the selected LNAPL

extraction technology, VEE, which is discussed in further detail in the following sections.


3.3.1 Process Design Criteria

This section provides the basis of design for the VEE system. The design approach and

calculations are presented in Appendix A. The following information obtained from the

treatability study provided the basis for the design of the full-scale VEE system:

• Radius of influence

• Well head vacuum

• Vapor extraction rate

• Total fluid extraction rate

• Vapor concentration

Radius of Influence

The vacuum Radius of Influence (ROI) was used to determine the spacing of extraction wells.

Vacuum measurements were collected during the treatability study in monitoring wells at

distances of 5 feet, 10 feet, and 15 feet from the extraction well. The ROI was estimated by

plotting the log of the vacuum versus the distance from the extraction well. The point at which

the curve intersects a pressure of 0.1 inches of water is the vacuum ROI. Based on the vacuum

data from the treatability study, a ROI of 18 feet was assumed for the NTCRA design.

Vapor Extraction Rate

An effective vapor extraction (air flow) rate of 35 cfm to 50 cfm at each well was established

during the treatability study for 1.5 inch drop tubes. However, a desire to minimize the required

vacuum pump size led to a change in the drop tube diameter to 1 inch for the full-scale

operation. By reducing the drop tube diameter to 1 inch, a lower flow rate is required to achieve

the critical velocity (velocity required to achieve a steady flow of fluid) of 2,800 fpm. Therefore,

the NTCRA design vapor extraction rate of 25 cfm to 30 cfm at each well was determined by

adjusting the data from a 1.5 inch diameter drop tube to the required rates for a 1 inch diameter

drop tube.

RI00468F 3-3 Beede Waste OH, NH

Well Head Vacuum

An effective well head vacuum of 100 inches of water at each well was established during the

treatability study for 1.5 inch drop tubes. By reducing the diameter of the drop tube from 1.5

inches to 1 inch, the vacuum must be increased in order to overcome greater friction losses.

Therefore, NTCRA well head vacuum of 160 inches of water at each well was determined by

adjusting the data from a 1.5 inch diameter drop tube to a 1 inch diameter drop tube.

Total Fluid Extraction Rate

The treatability study focused on the Former Lagoon, the Former LIST/AST, and the SWRP-2

plumes. One extraction well was installed in each of these plume areas and the average total

fluid (groundwater and LNAPL) extraction rates in each well ranged from 0.005 gpm to 0.228

gpm.

Based on this data, a conservative maximum fluid flow rate of 0.25 gpm per well was selected to

perform transmission line headless calculations for the NTCRA design. The low range of

average fluid flow rate (0.005 gpm) was used to size the storage vessels. TtNUS will make a

conscious effort to minimize groundwater extraction during operation by positioning the drop

tubes above the water table in extraction wells, particularly when the LNAPL layer is thin.

Vapor Concentration

The average daily VOC loading in the extracted soil vapor ranged from approximately 0.04 Ibs

in the Former AST/UST/SWRP #2 Area to 1 Ib in the Former Lagoon Area during the treatability

study. The loadings were based on average measured flow rates of 40 cfm and 33 cfm,

respectively, and one extraction well operating at a time during the treatability study.

The NTCRA design flow rate for each well is 25 cfm to 30 cfm. Adjusting the treatability study

data to account for the lower flow rates (assuming a linear relationship), the average daily VOC

loading rate would be expected to range between a minimum of 0.025 Ibs/day and a maximum

of 0.91 Ibs/day, per well.

It is anticipated that 48 wells will be operating concurrently during the NTCRA; therefore, the

estimated total soil vapor VOC loading to the VEE system is expected to range between


approximately 1 2 Ibs/day and 44 Ibs/day. The VOC loading at any one time will primarily

depend upon the locations and flow rates of the extraction wells operating at that time

TtNUS conferred with the New Hampshire Department of Environmental Services (NHDES)

regarding the projected VOC emissions from the system NHDES reviewed the predicted VOC

emissions data provided by TtNUS and concluded that, even without vapor treatment, the

annual air emissions from the system would not exceed New Hampshire's emission limits for

non-exempt VOCs or hazardous air pollutants (HAPs) and the daily and annual emissions of

toxic air pollutants from the system would be below their respective Ambient Air Limits (AALs)

Therefore, neither treatment or monitoring would be required to meet state air quality

regulations. (NHDES, 1999)

However, in accordance with EPA New England policy, vapor treatment is included in the

system to minimize VOC emissions to the air. The soil vapor stream will be treated by vapor

phase granular activated carbon (GAC) prior to discharge to the atmosphere. The air entering

and exiting the GAC unit will be monitored daily using a photoionization detector (PID) or flame

lonization detector (FID) to ensure that VOC discharges are minimized. When VOC

breakthrough is detected the vapor stream will be diverted to a backup GAC unit. The details of

the air monitoring program will be provided in the Quality Assurance Project Plan

(QAPP)(TtNUS, 1999) and NTCRA Operations Plan

3.3.2 Process Treatment Scheme

The goal of the NTCRA is to remove as much mobile LNAPL from the surface of the aquifer as

possible. To achieve this goal, the VEE process is designed to be a flexible system that allows

the operator to make adjustments in order to maximize the recovery of LNAPL

The VEE system design incorporates two parallel equipment trams that are housed in separate

equipment enclosures. One equipment train services the Former Lagoon area plume and the

southern sections of the Former AST/UST/SWRP-2 plume and the SWRP-1 plume. The other

equipment train services the central and northern sections of the latter two plumes.

The equipment trains are identical and the primary components of each tram include a vacuum

pump, an air/water separator, an oil/water separator, a heat exchanger, and a vapor phase


granular activated carbon (GAC) unit. The vacuum pump creates the vacuum in each extraction

well that induces the flow of LNAPL, groundwater, and soil vapor to the equipment train.

The equipment trains are connected to a combined total of 143 extraction wells by a network of

polypropylene transmission piping. The equipment and piping network is designed so that one

third of the wells (approximately 48) will be operating at any given time. The well and piping

network will be divided into 6 zones - 3 connecting to each treatment train. Two of the 6 zones

- one from each treatment train - will operate at once.

The operation will be cycled among the 3 zones in each system to maximize LNAPL collection

and minimize groundwater collection. The selection of wells in each zone will be dynamic, and

will depend on system performance and field measurements of LNAPL thickness. For example,

wells containing little LNAPL may be operated less frequently than those containing a thick

LNAPL layer, and wells no longer producing LNAPL may be closed off entirely.

Polypropylene was selected as the material for the transmission piping for chemical

compatibility with the LNAPL. The piping will be heat traced and insulated to prevent freezing of

extracted groundwater during the winter months of operation. The header lines will be graded

toward the VEE equipment to allow gravity flow of extracted fluids and to prevent low points in

the pipelines where fluid can accumulate and disrupt the flow of air.

Polyethylene was selected as the material for the drop tubes for its flexibility and chemical

compatibility with the LNAPL. The drop tubes will be heat traced and insulated to prevent

freezing of extracted groundwater during the winter months of operation. The drop tubes are

designed with flexible connections to the extraction wells to allow vertical adjustments. The

drop tubes will be manually adjusted as the LNAPL thickness or groundwater elevations

fluctuate.

The equipment train is designed so that the LNAPL, groundwater, and soil vapor mixture

extracted from the wells first passes through an air/water separator to protect the vacuum pump

and GAC vessels from exposure to the extracted fluids. The air/water separator also prevents

emulsification of the LNAPL in the groundwater, which commonly occurs when such fluids are

passed through a vacuum pump.


3.3.3

The soil vapor exits the top of the air/water separator and passes through the vacuum pump

and a heat exchanger prior to entering the vapor phase GAG units. As a result of heat transfer

from the pump, the soil vapor stream may reach temperatures upward of 300° F. Since the

PVC components of the GAC units can begin to lose integrity at 125° F, the heat exchanger has

been included in the design on the discharge side of the vacuum pump to reduce the

temperature of the air stream prior to entering the GAC units. The heat exchanger uses

ambient air to cool the process air.

The fluids separated from the soil vapor in the air/water separator pass through an oil/water

separator to separate the mixed fluid stream into separate LNAPL and water streams, which are

then transmitted to separate storage tanks to await off-site disposal. The oil/water separator is

included to minimize disposal costs, because a mixed oil/water stream would be much more

costly to dispose of than the oil and water individually.

Off-site disposal of groundwater was selected as a less costly and more implementable

alternative to treating and discharging the groundwater on site. Because of the relatively small

volume of water expected to be generated (approximately 20,000 gallons per month), the short

duration of system operation, the mixture of contaminants in the groundwater, the close

proximity of private potable water supply wells, and resulting limited options for on-site

discharge, off-site disposal was considered a better and less costly alternative. Off-site disposal

of LNAPL was the only viable alternative for disposal of the LNAPL, which contains PCBs and

chlorinated solvents and may be classified as TSCA and/or RCRA regulated waste.

Performance Requirements

The removal action objective of the VEE system is to extract as much mobile LNAPL as possible

from the surface of the groundwater. The volume of LNAPL has been estimated at approximately

43,000 gallons based on data obtained from the treatability study (B&RE, 1998a). This volume is a

rough estimate based on approximated LNAPL thickness from a limited number of wells within the

three plumes. The actual volume of mobile LNAPL may be significantly more or less than 43,000

gallons. It is estimated that approximately 50% of the LNAPL, or 21,500 gallons, will be recovered

by the VEE System; the remaining LNAPL is expected to become immobilized within the soil pores

as the LNAPL saturation decreases (refer to Section 4.4 for additional discussion on this issue).


In order to monitor the progress of the VEE system, the groundwater and LNAPL levels in the

system extraction wells will be measured on a regular basis during operation. The VEE portion of

the NTCRA will be considered complete when there is no measurable product in any of the

extraction wells, or when the LNAPL recovery rates have diminished to the point where it is no

longer considered practical to continue recovery efforts. It is estimated that the removal action

objectives will be completed in 5 to 9 months.

Another performance requirement to be met during the operation of the VEE system pertains to the

control of VOC emissions. The extracted soil vapor is treated, prior to discharge, by vapor phase

granular activated carton (GAC). Sampling ports are included in the air discharge line entering

and exiting the GAC unit. The air stream VOC concentrations will be measured by a PID/FID on a

regular basis to ensure that a 90 percent removal rate is maintained by the GAC unit. When the

removal rate is determined to be less than 90 percent the air stream will be switched to the backup

GAC unit. Emission and ambient air monitoring are discussed in further detail in the QAPP

(TtNUS, 1999).

3.3.4 Residuals Management and Disposal

Residuals that will be generated during site preparation, construction, and operation of the VEE

system include cleared trees and brush; contaminated soils from drilling and other intrusive

operations (e.g., road grading, installation of drainage controls, etc.); contaminated

groundwater; LNAPL; spent carbon; personnel protective equipment (PPE); and

decontamination water. Contaminated soils (to be dewatered, if necessary) and petroleum-

contaminated vegetation will be stockpiled on-site (placed on an impermeable liner and covered

by a secure, impermeable tarp). Contaminated groundwater and decontamination water,

LNAPL, spent carbon, and PPE will be contained and stored on-site, prior to off-site disposal.

Uncontaminated trees and brush will be chipped and stored on-site.

3.4 Passive Interceptor Trench Design Basis

The interceptor trench extension is designed to the same specifications as the 100-foot long

interceptor trench that was installed during the treatability study. The extension lengthens the

original trench by 24 feet to the west to contain the portion of the plume that is not intercepted by

the existing trench. It is not necessary to extend the interceptor trench to the east since the plume


3.4.1

in this area is addressed by the VEE system and is not in imminent danger of breaking out into the

wetlands.

Process Design Criteria

The main design criteria for the interceptor trench, a passive technology, are the width of the plume

to be intercepted, the depth of the LNAPL, and the physical properties of the LNAPL. These

criteria are discussed in this section.

Trench Design

Since the existing 100-foot interceptor trench (installed during the treatability study) did not extend

to the western limit of the plume migrating toward the Kelley Brook wetlands, it was determined

that a 24-foot extension of the trench to the west was needed to contain the plume. The length of

the extension was determined based on the results of previous investigations including a soil

investigation during the treatability study. Three soil borings were advanced to the water table with

a 2-inch diameter hand auger at 5-feet, 10-feet, and 15-feet intervals west of the existing

interceptor trench. The soil at 5-foot and 10-foot locations was a black stained silty sand with a

sheen on the saturated soils. There was no evidence of LNAPL at the 15-foot location (B&RE,

1998a); however, the groundwater data suggested that the plume may extend to, or slightly

beyond, this point. Since concrete galleys for the trench are constructed in 8-foot segments, it was

determined that a 24-foot extension would provide adequate containment.

The bottom of the trench is set at approximately 105.5 feet above mean sea level (MSL), or 2 feet

below the lowest observed water table elevation in the area. This elevation is intended to ensure

that the top of the water table and bottom of the LNAPL layer remain within the trench through the

seasonal water table fluctuations (typically less than one foot).

The trench design, an open-channel type, was selected during the treatability study as an

alternative to a traditional gravel-filled trench to facilitate testing of the effectiveness of the

interceptor trench technologies. Eliminating the gravel within the trench increases the rate and

volume of LNAPL recovered by significantly reducing the surface area of media that the LNAPL

must travel through and "wet" before reaching the recovery equipment. Additional short-term and

long-term benefits of the open channel design include easier observation of product presence


within the trench and less likelihood of failure due to clogging of the gravel (B&RE, 1997). Because

the design was effective in treatability testing it made sense to extend the trench for the NTCRA

rather than changing the design.

The LNAPL interceptor trench is constructed of constructed of pre-cast concrete galley structures

laid end to end in an excavated trench to form a continuous channel. The galley chambers have

open ends to allow formation of a continuous channel (except the two end sections which are

closed at the outer end) and perforated sides that allow the LNAPL to flow directly into the open

channel collection area of the trench. An impermeable geomembrane is installed on the

downgradient side of the chambers to ensure that LNAPL can not migrate beyond the trench. The

impermeable geomembrane is situated to intersect approximately the top 2 to 3 feet of

groundwater so that it provides an effective barrier against LNAPL migration, but does not

significantly alter the hydraulic gradients {B&RE, 1997). The galley chambers also have an open

bottom that allows the water table to fluctuate naturally and minimizes groundwater mounding by

not restricting the flow of water around/beneath the impermeable membrane.

Passive Skimmers

Three in-trench LNAPL collection technologies, including passive skimmers, skimmer pumps,

and a dual pump system, were evaluated during the treatability study. The passive skimmer

was the most effective for LNAPL removal while minimizing the collection of groundwater.

Passive skimmers also have the advantage of not requiring a power source, and they can be left

unattended for days provided they have adequate canister capacity (B&RE, 1998a).

The passive skimmer selected for the NTCRA is the same model that was tested and performed

well during the treatability study: the Filter Bucket™ skimmer manufactured by ORS Environmental

Equipment. The skimmer consists of a floating hydrophobic-oleophilic filter cartridge, a flexible

product tube, and a product collection canister with a handle and a removable lid. The filter

cartridge floats at the product-water interface and automatically adjusts to any groundwater

fluctuation within its travel range (0 to 8 inches). Hydrocarbons enter the skimmer through the filter

cartridge that allows product with a specific gravity of less than 1.0 to pass, but repels water.

The filter cartridge is available in assorted mesh sizes, and the correct mesh size for an application

is determined by the viscosity of the product (LNAPL) to be collected. During and following the


treatability study, two types of filters were tested a 100-mesh filter designed to collect LNAPL with

viscosities of up to 16 centiStokes and a 60-mesh filter designed to collect LNAPL with viscosities

between 16 and 60 centiStokes Based on short-term performance, both cartridges appeared to be

equally effective in recovering LNAPL and minimizing collection of LNAPL

The viscosity measurements (collected by B&RE personnel between December 5 1996 and

January 13, 1997) of the LNAPL in the plume adjacent to the interceptor trench, ranged from 20 to

50 centiStokes As a result of the treatability study results and the viscosity data the 60-mesh filter

cartridge was selected for the NTCRA (B&RE, 1998a)

3.4.2 Performance Requirements

The removal action objective of the interceptor trench system is to prevent the continued migration

of mobile LNAPL into the Kelley Brook wetlands The performance requirements for the trench are

to intercept the full width and depth of the LNAPL plume, and to recover the LNAPL in the trench to

the maximum extent possible The passive recovery portion of the NTCRA will be considered

complete when the LNAPL is no longer observed in the trench and the passive skimmers

consistently fail to collect LNAPL In the event that only a sheen of LNAPL is present on the surface

of the water in the trench (which would not be effectively removed by the passive skimmers),

adsorbent pads will be used to remove the LNAPL until there is no longer a sheen present or it is

determined that continued maintenance of the trench is not necessary

3.4.3 Residuals Management and Disposal

Residuals that will be generated during site preparation, construction, and operation of the

LNAPL interceptor trench include cleared trees and brush, contaminated soils from trench

excavation activities, LNAPL, PPE, and decon water Contaminated soils (to be dewatered, if

necessary) and petroleum-stained vegetation will be stockpiled on-site (placed on an

impermeable liner and covered by a secure, impermeable tarp) Decontamination water,

LNAPL, and PPE will be contained and stored on-site, pnor to off-site disposal Clean trees and

brush will be chipped and stored on-site


4.0 NTCRA PROCESS DESIGN DESCRIPTION AND ANALYSIS

This section provides detailed descriptions of the NTCRA system components and an analysis of

system operation, ARARs compliance, and expected system performance

4.1 VEE System

The VEE System is designed to meet the NTCRA objective of actively recovering the mobile

LNAPL present on top of the surficial aquifer at the site The VEE system design incorporates a

liquid ring vacuum pump to extract LNAPL, along with groundwater and soil vapor, from site

extraction wells iff a high velocity stream The system also includes equipment to separate the

extracted mixture, to treat the separated air stream, and to store the separated LNAPL and

water streams

The following sections provided a detailed description of the VEE components and VEE system

operation

4.1.1 Subsystems Description

The VEE system is composed of several subsystems that include

• Extraction Wells and Network

• Extraction Equipment

• Transmission Equipment

• Separation Equipment

• Air Treatment Equipment

• Groundwater Storage/Off-Site Disposal

. LNAPL Storage/Off-Site Disposal

Each of these subsystems is described further in the following paragraphs


Extraction Wells and Network

The well layout is based on the estimated 18-foot ROI established in the treatability study and

the need to overlap the ROIs somewhat to minimize "dead zones" in the plumes (spots not

influenced by any well), while avoiding excessive overlapping that may result in wells competing

against each other

The three LNAPL plumes encompass an area of over 2 acres Using the 18-foot ROLand

spacing the wells approximately 30 feet apart, 143 extraction wells are required to cover the

three plumes (see Figure 4-1)

The wells are 4-inch djameter polyvmyl chloride (PVC) with 7 5 feet of screen, positioned to

span from 2 5 feet above the seasonal high water table to 2 5 feet below the seasonal low water

table A 1-inch diameter polyethylene drop tube with perforations in the bottom 12 inches is

installed within the extraction wells The other end of the drop tube is connected to a

transmission line The drop tube is held in position within the extraction well using a rubber

reducer fitting The elevation of the drop tube can be easily adjusted to account for fluctuations

in the water table or changes in LNAPL thickness In general, the drop tube will be situated just

above the water table, within the LNAPL layer

Each extraction well requires an air flow rate of 25 - 30 cfm in order to "lift" LNAPL and

groundwater out of the well Operating all 143 wells simultaneously would require a vacuum

pump capable of a 4,300 cfm flow rate while generating a vacuum of 20 - 24 inches of mercury

A vacuum pump operating at these parameters would require a 300 Hp motor Since

equipment of this scale would be expensive and impractical to operate, a decision was made to

subdivide the 143 wells into zones, and cycle the operation of these zones

After evaluating different combinations of wells and pump sizes, TtNUS determined that

operating a third of the total wells (48 wells) with two separate equipment packages (each with a

50 Hp vacuum pump) was the most practical and cost effective alternative

The 143 wells were subdivided into a total of 6 zones, see Figure 4-2 Two of the 6 zones will

operate at any given time - one by each equipment package Isolation valves were placed at

key locations along the transmission pipelines so that a minimum number of valves would have

to be turned to change zones of operation Additionally, all the extraction wells are equipped


with individual isolation valves providing flexibility in modifying the configuration of the zones as

well as providing the ability to shut off wells no longer producing LNAPL.

Extraction Equipment

The design flow rate for each extraction system was based on extracting approximately 30

cfm/well from 24 wells at a time (48 wells with both equipment trains operating). The pumps

selected to produce this flow are two 50 Hp oil-sealed liquid ring vacuum pumps. This vacuum

pump is capable of generating 26-inches of mercury vacuum at its inlet, while pumping

approximately 770 cfm and producing a vacuum of up to 160 inches of water at the drop tube.

The liquid ring vacuum pump is the primary mechanism for the removal of LNAPL, groundwater,

and soil vapor from the subsurface. The anticipated air and fluid flow rates per extraction well

are 25 to 30 cfm and 0.005 to 0.25 gpm, respectively.

Transmission Equipment

Once the mixture of soil vapor, LNAPL, and groundwater is lifted out of the extraction well, it is

conveyed through a network of small diameter lateral pipes and large diameter header pipes

(1.5-inch to 8-inch lines) (Figure 4-3). The header pipes are graded toward the equipment to

prevent low points in the pipelines where fluid can accumulate and disrupt the flow of air.

Headless calculations were performed to size pipe diameters in order to minimize vacuum

reduction due to friction and other loss factors. Polypropylene pipe was selected for the

transmission piping because of its chemical compatibility with the LNAPL constituents. The

transmission pipe is installed with heat tracing and insulation to prevent the freezing of extracted

groundwater during operation through the winter months.

The VEE system design also includes pumps to transfer LNAPL and groundwater from the

oil/water separator (described below) to their respective storage tanks. A 5 Hp reciprocating-

type air compressor, designed to supply 20 cfm of 100-psig air, provides the compressed air

requirements for the transfer pumps. The compressor contains pre- and post-air filters and is

mounted on a single 80 gallon pressure receiver tank, which provides compressed air surge

capacity.


Separation Equipment

The mixture of soil vapor LNAPL, and groundwater is transported to the air/water separator by

transmission piping The air/water separator protects the vacuum pump from exposure to the

extracted fluids and prevents the emulsification of LNAPL in the groundwater which is a

common result of passing the fluids through a vacuum pump

The air/water separator is a two-tank design in which the tanks are mounted vertically, one above

the other The extracted soil vapor exits the top tank while the LNAPL and groundwater are

collected in the bottom tank See Figure 4-4 for a Process Flow Diagram

The top tank accommodates air and liquid flow rates of 1,000 cfm and 16 gpm, respectively, and a

maximum static vacuum of 26 inches of mercury The bottom tank is a collection chamber with a

minimum capacity of 50 gallons and is installed with low level, high level, and high-high level

floats

A high level "ON" switch within the air/water separator automatically operates a series of

solenoid valves, which disengage the two tanks, then pressurize the bottom tank with

compressed air The compressed air displaces the LNAPL and groundwater to an oil/water

separator A low level "OFF" switch reverses the solenoid valves after emptying the air/water

separator and re-engages the vacuum to the bottom tank

The oil/water separator is a secondary water treatment device that coalesces and removes free

phase oils and petroleum hydrocarbons from water streams The oil/water separator operates

most effectively with a laminar influent flow, is located downstream of the air/water separator,

and is designed for a fluid flow rate of 16 gpm

The oil/water separator is an epoxy-hned carbon steel tank equipped with weirs to regulate

liquid flow and prevent breakthrough of separated product, an adjustable skimmer, coalescing

plates, oil storage chamber, discharge pumping chamber, sludge clean-outs, vapor-tight lid and

vent assembly, and a hazardous location float for overflow protection


Air Treatment Equipment

The operation of the liquid ring vacuum pump will result in considerable heat generation and the

air stream discharge temperature may be as high as 300° F Temperatures of this magnitude

will damage the internal PVC components of the GAC units To prevent this damage from

occurring, a 1,000 scfm heat exchanger is located on the discharge side of the pump to cool the

air stream prior to entering the GAC units A 3 Hp motor is used to operate a 24-inch fan that

supplies ambient air to cool the process air to within 15° F of ambient temperature

Once the air is cooled by the heat exchanger, it is forced through two vapor phase GAC units in

series to remove VOCs from the air stream Each GAC unit contains 2,000 Ibs of carbon and is

designed for a maximum flow rate of 1,000 cfm

Groundwater Storage/Off-Site Disposal

Water from the oil/water separator is pumped from the water sump via a pneumatic diaphragm

transfer pump to the water storage tank The tank has the capacity to store 20,000 gallons, the

estimated volume to be generated from one month of operation

The tank floor, sides, and roof are constructed of 3/16-inch steel plate The sides are v-cnmped

for strength and stability, and the roof is reinforced with 3-inch rafters Access hatches are

located on the top and end of the tank and a ladder and manway is located on one end to allow

access the top hatch

The water is stored in 1he tank prior to off-site disposal in a permitted facility compliant with all

state and federal regulations

LNAPL Storaqe/Off-Site Disposal

LNAPL from the oil/water separator is pumped to the LNAPL storage tank via a pneumatic

diaphragm transfer pump The LNAPL storage tank has a storage capacity of 5,000 gallons It

is double wall construction, compatible with a wide range of fuels, and includes built-in

secondary containment and interstitial leak monitonng capabilities

RI00468F 4-5 Bee

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